1. Field of the Invention
The present invention relates to a power cord extraction part structure of an electric apparatus, and more particularly, in an electric apparatus in which an electric circuit unit applied with high voltage is accommodated in a casing made of sheet metal, to a power cord extraction port structure of the electric apparatus in which the power circuit unit is covered with an integrally formed protective cover made of resin to extend the linear distance (interval) or a creepage distance from the casing to tall components or soldered portions of the power circuit unit, thereby improving safety or electric properties.
2. Description of the Related Art
In recent years, in an electric apparatus such as a DVD drive, thinning and flattening of a casing of the electric apparatus have remarkably been promoted. Moreover, in case of the casing made of sheet metal, it is demanded to ensure safety or electric properties by securing a distance between a top plate, a bottom plate or side plates constituting an outer plate of the casing and a power circuit unit accommodated in the casing to be sufficiently large or lengthening a creepage distance between the top plate, bottom plate or side plates of the casing and the power circuit unit, thereby securing safety in use and electric properties.
In order to meet the above-described demand, there are provided various measurements in which a height dimension of tall components is made as low as possible to enlarge or secure a distance between the power circuit unit and the top plate of the casing or the like, thereby improving safety or electric properties, or an insulating sheet is attached to a rear surface of the top plate of the casing to ensure safety in use or electric properties.
However, in an electric apparatus in which a top plate, a bottom plate or side plates of a casing is made of sheet metal, when the tall components such as capacitors having small height dimensions are used as a measurement to attempt thinning and flattening of the casing while securing safety in use and electric properties, the tall components are expensive to let the cost high. Furthermore, in case of employing the measurement in which an insulating sheet is attached to a rear surface of the top plate of the casing or the like, required safety or electric properties cannot be maintained when the insulating sheet is removed.
Therefore, the inventors have repeatedly and intensively studied to sufficiently ensure electric insulation between the top plate of the thinned and flattened casing and the power circuit unit without using expensive tall components having low heights. As a result, it has been found that by covering the power circuit unit with the integrally formed protective cover made of resin, the top plate of the thinned and flattened casing or the like is prevented from contacting the tall components such as capacitors by the protective cover so that electric insulation between the casing and the power circuit unit is sufficiently ensured, as disclosed in Japanese Utility Model Registration No. 3,128,387. The protective cover disclosed in Japanese Utility Model Registration No. 3,128,387 is provided in an inner corner portion of the casing made of sheet metal, and includes an upper plate interposed between the top plate of the casing and the power circuit unit, a lower plate disposed at a lower side of wirings of the power circuit unit, and a rear plate interposed between an back plate of the casing and the power circuit units.
Meanwhile, there is a suggestion that in order to prevent an AC cord from contacting a chassis of the casing made of an iron plate, a drawn portion of the AC cord in the casing is held in place by a wire holding member, as disclosed in Japanese Patent Publication No. 2002-319773A. Furthermore, there is a suggestion for a structure of fixing a power cord in the case where the power cord is extracted to a rear side of a casing, as disclosed in Japanese Patent Publication No. 2002-134950A.
However, the electric apparatus in which the protective cover is provided as described in Japanese Utility Model Registration No. 3,128,387 generally employs the configuration in which the power cord connected to the wiring board of the power circuit unit is inserted into a power cord extraction port formed in a back plate of an outer plate of the casing to be extracted to the outside of the casing. Therefore, under the situation in which a drawn portion in the casing formed from a front end of the power cord connected to the wiring board to an extraction start end inserted through the power cord extraction port is positioned at a side portion of the protective cover, since the drawn portion of the power cord in the casing faces a confronting space between the upper plate and the lower plate of the protective cover, the drawn portion in the casing enters the confronting space, and thus may contact the electric components of the power circuit unit. When such contact occurs, the safety may not be ensured.
Accordingly, a configuration in which the drawn portion of the power cord in the casing is held by a wire holding member disclosed in Japanese Patent Publication No. 2002-319773A may be taken into consideration. However, in such case, there is a problem in that the wire holding member is excessively required and the number of necessary components is increased to increase fabricating processes, thereby decreasing mass productivity in a fabricating line or raising the cost. Furthermore, a configuration in which a double coated cord or the like subjected to high insulating treatment is used as the power cord may be taken into consideration. However, there is also a problem in that such a power cord itself is expensive to cause the increase in cost of the electric apparatus.